Coverage is currently not supported with the meson build system,
removing from .gitlabci to reduce usunsed code.

Meson detects something has changed when using build artifacts
from previous build and performs a rebuild.

Hide the rebuild info, since it has no new information and the
build already passed in the previous stage.

Since the build takes <10s, it's probably not worth investigating
whether it's possible to avoid it.

Since these tests are very quick, it's not worth it to have a separate
job for them, it only wastes CI resources.

-Wpedantic is only enforced in CI, as we only have it fixed with c11
standard, and I didn't want to force c11 dependency for everyone yet.